Swine Flu

From the Washington Post:

“The World Health Organization rushed to convene an emergency meeting Saturday to develop a response to the “pandemic potential” of a new swine flu virus that has sparked a deadly outbreak in Mexico and spread to disparate parts of the United States.

Health officials reported that at least eight students at a private high school in New York City had “probable” swine flu. They also confirmed three new cases — two in Kansas and one in California — bringing the total number of confirmed U.S. cases to 11. The president of Mexico, where the outbreak has killed as many as 81 people, issued an order granting his government broad powers to isolate patients and question travelers. (…)

The virus, for which there is no vaccine for humans, has nearly brought Mexico City to a halt. Normally congested downtown streets in this city of 20 million were almost empty Saturday, and of the few people who ventured outside, many said they did so only out of necessity. Soldiers posted at subway stations handed out face masks to passersby from the back of armored vehicles. Some pedestrians covered their mouths and noses with scarves and rags.

“We can’t escape the air,” said Antonio Gonzáles, 56, who wore a surgical mask outside a public hospital. “If it was something in the food, we’d have a chance.”

The Mexican government reported more than 1,300 suspected cases of the virus, which mixes animal and human strains of flu. Bars and nightclubs, schools, gallery openings and sporting events were cancelled until further notice. Authorities advised people to wash their hands regularly and avoid the customary greeting of kissing on the cheek. The government issued a decree giving the Health Ministry power to enter people’s homes, close public events, isolate patients, and inspect travelers and their baggage.

The Associated Press reported that 24 new cases of the flu emerged Saturday in Mexico.”

Thus far, the Mexican version seems to be much more virulent than the US version, despite the fact that “partial comparisons of the genetic sequences of the Mexican and American cases shows them to be essentially the same”. There could be any number of explanations for this: “some difference in the information (looking at severely ill versus routine surveillance of outpatients), some difference in the virus (while the viruses are said to be “genetically identical” this is true only in the parts that have so far been compared) or some co-factor (e.g., co-infection with another pathogen).”

However, it seems likely that there has been human-to-human transmission, which is worrisome. Moreover, the casualties in Mexico seem to have been disproportionately healthy young adults. On NPR today, Laurie Garrett gave two possible explanations for this: it might be that children and the elderly got the regular flu vaccine, and that it confers some protection to this new strain of influenza, which would be good; or it might be the dreaded cytokine storm: basically, a lethal overreaction by the immune system. This is thought to be the reason why young adults were disproportionately represented among the casualties of the pandemic of 1918: since they have stronger immune systems, the overreaction was more likely to be fatal.

If we’re lucky, this will continue to be relatively mild in this country, and the steps Mexico is taking will do the trick. Just in case, though, now might be a good time to download this flu manual (pdf; h/t DemFromCT at dKos.) Unnecessary preparation beats being caught unprepared by a flu pandemic.

Good blogs on this topic: Effect Measure, H5N1, Aetiology, DemFromCT at dKos, ScienceInsider.